Wiring question - pump switch on negative lead

[BrentwoodBayliner]

Hello wise and all-knowing forum..

I've just discovered the console switch which controls the macerator pump on my Bayliner 3270 is wired into the negative lead.

It seems to work fine. I guess it completes the circuit, but probably not the way it should be.

Based on the look of the switch and the way it's mounted I'd say it's not 'factory'.. a previous owner has added it.

Interestingly, the wires to-and-from the switch are red. But the one which 'feeds' the switch comes directly off the negative buss post on the nearby fuse panel. One red wire surrounded by black wires..

Has anyone ever encountered this? Thanks for your input!

 

[Comodave]

Where is it getting the positive voltage from? I would trace the other side down and see. The switch (and fuse/breaker) should be on the positive side. Then to the pump and a black negative wire back to the ground bus bar. Sounds like you have a small project to do. Make sure the wiring is large enough to give you good voltage to the pump. Measure the total wire distance from the positive source to the ground bar then lookup and see what gauge wire you need to give no worse than a 10% drop, but I prefer a 3% drop so I go to the larger size wire. It is a small one time cost to go to the larger wire but your pump will run better on a 3% drop.

 

[twistedtree]

I think the risk of having the positive lead always energized is electrolysis. There are a bunch of "ifs" that would have to happen, but it is a boat...


In a nut shell, if the positive wired has a electrical path to the water body that the boat is in, it can cause electrolysis, and that can be very damaging to metal parts, very quickly. Whether there is an electric path depends on the construction of the pump, you plumbing, etc. But a classic cause of electrolysis is a bilge pump wire with a compromised connection of insulation submerged in bilge water.

 

[Frosty]

Interestingly, the wires to-and-from the switch are red. But the one which 'feeds' the switch comes directly off the negative buss post on the nearby fuse panel. One red wire surrounded by black wires..

Don't mind me if you already know this and have discounted it, but if it is a lighted switch, then there is often a negative lead to the switch, which feeds the light. Then the rest of the switch is positive wires as expected. Just mentioning this in case it's the situation. (At least this is how my recently added Contura switches work; the previous unlighted switches just had positive wires as you'd expect; I needed to add a negative lead due to the LED lights in the switches.)

 

[O C Diver]

I would have to change it. It drives me nuts when people can't follow the simplest wiring standards for conductor coloring and switch replacement. While you caught it quickly, the next person to replace that pump might wire the pump leads backwards because of it.

Ted

 

[BeeJay]

Ohps, posted on wrong thread. Sorry